Hair heightener



FIG. 1 is a front perspective view of a hair heightener showing my new design;

FIG. 2 is a top plan view thereof;

FIG. 3 is a bottom plan view thereof;

FIG. 4 is a front view thereof;

FIG. 5 is a left side view thereof;

FIG. 6 is a right side view thereof; and,

FIG. 7 is a back view thereof. 

The ornamental design for a hair heightener, as shown. 